T-Mobile has confirmed it has suffered a data breach following reports that information for 100 million customers is for sale online.

News broke yesterday that a hacker was trying to sell T-Mobile customer information. The hacker claimed to have gained access to T-Mobile servers, copying and backing up the data before he was locked out.

T-Mobile issued a statement saying they were investigating the claims, but the company has now confirmed the breach occurred.

We have determined that unauthorized access to some T-Mobile data occurred, however we have not yet determined that there is any personal customer data involved. We are confident that the entry point used to gain access has been closed, and we are continuing our deep technical review of the situation across our systems to identify the nature of any data that was illegally accessed. This investigation will take some time but we are working with the highest degree of urgency. Until we have completed this assessment we cannot confirm the reported number of records affected or the validity of statements made by others.

We’ll provide updates as T-Mobile does.